Where its great that the LSAT is so dramatically lighter than its predecessor, our armed forces seem to always replace something much lighter with some other gadget that becomes mandatory, making the load heavier (again). While the Taliban (etc.) travel really light, our guys have huge packs/loads to carry around that inhibits their mobility.

While I applaude the efforts made to lighten the load - they needs to *really* lighten the load.

If they are going through this much trouble, why not develop a 6.8mm or 6.5mm round to replace the 5.56mm? If they are going to have to make all new guns in the first place for this round, might as well improve it all around.

If they are going through this much trouble, why not develop a 6.8mm or 6.5mm round to replace the 5.56mm? If they are going to have to make all new guns in the first place for this round, might as well improve it all around.

At this point they are just testing the gun and plastic cased ammunition concepts, the two concepts are linked so they cannot be separated. The advantage of duplicating the 5.56mm round is that you have a well established baseline to evaluate it against. They will, however, adopt the new weapons using the current 5.56mm round will occur only if a new round is not accepted.

OK, that last sentence sounds screwy. But, there have been RFPs for new gun calibers proposed, submitted, amended, withdrawn, re-proposed, etc. and ad nauseam. The problem is assigning the weighting criteria for the different performance factors used to make the selection, so the various offerings can be optimized. Only when these criteria have been finalized and documented to everyone’s satisfaction (hah!), and locked in, can testing and selection proceed. Until then nothing will happen.

Here are a few of the tradeoffs. Which is more important:

• Long range performance vs. short?

• Penetration vs. energy dump?

• Performance vs. body armor? What kinds of body armor?

• Optimized for which barrel length?

• Accuracy or compactness?

• How do you rank the above versus each other?

And some of the above are mutually exclusive.

There are so many criteria and such divergence of opinions about which is ‘best’ that the selection process for the new round is likely to make the recent air tanker selection controversy look like a preschool brawl in a sand box. Personally, I suspect that the Pentagon may be going ahead with the field trials in 5.56mm to put pressure on the holdouts that if they don’t come to a compromise on the selection criteria that there won’t be a new caliber selected and the old 5.56mm equivalent will be adopted by default.

If a lump of powder could be formed into a solid but porous shape with a good burn rate, for example like open cell foam, with structural integrity and married, perhaps threaded,m to the bullet, then it could be electrically ignited in the chamber, leaving no permanent residue, then their might be a case for caseless, possibly rendering brass obsolete.

If a lump of powder could be formed into a solid but porous shape with a good burn rate, for example like open cell foam, with structural integrity and married, perhaps threaded,m to the bullet, then it could be electrically ignited in the chamber, leaving no permanent residue, then their might be a case for caseless, possibly rendering brass obsolete.

The problems with caseless ammunition from the beginning have been:

1) – Moisture absorption. The porous material is a no-no here. Even if the propellant is totally non-absorbent moisture will be trapped in the cell structure, producing erratic performance. It would also increase the bulk of the ammunition.

2) -- Vulnerability to ignition in bulk. It is a caseless propellant block, no way around it. But they have gotten it to the point there is no explosion problem unless very confined.

3) – Vulnerability to damage. The propellant is brittle. I know you specified structural integrity, but strength and deflagrate materials fon’t seem to go together. In addition you specify putting it behind the bullet. The increase length to diameter ratio makes it more vulnerable to breakage.

4) – Breach seal requirements. Cased ammo provides a disposable gasket seal, a means of extracting duds, and fixed head spacing. Caseless does not, requiring an entirely new design. Current designs seem to favor swinging or rotary designs with pressure activated seals, which are poorly suited for a longer round like you propose.

The method everyone seems to have settled on is case telescoped design with the bullet imbedded in a block of brittle solid propellant that is pulverised by the primer detonation with a consumable coating for added moisture resistance, flame resistance, and durability, then pack it in sealed clips for rifles and sealed containers for machineguns. No reloading clips and no topping off in combat.

The last item is the electric primer, which is too vulnerable to static discharge. The electric primers used on cannon and such get around the problem by just requiring more energy to detonate than the typical static discharge can provide, but this is not practical due to the limited power storage on an infantry weapon. It also severely limits the rate of fire to the charging rate of the firing circuit and the maximum draw on the batteries.